They used dark forces

'Before there was James Bond, there was Gregory Sallust.' Tina Rosenberg, Salon.com They Used Dark Forces is the eighth in Dennis Wheatley's bestselling Gregory Sallust series featuring the debonair spy Gregory Sallust, a forerunner to Ian Fleming's James Bond. It is 1943 and secret agent Gregory Sallust parachutes into Nazi Germany. In the company of an ex-Bolshevik General, the two of them join forces with the widow of a German diplomat who is in contact with Allied Intelligence. It is through her that Gregory becomes unwillingly involved with a Black Magician. Sixteen months later they meet again and decide to pool their knowledge of the dark arts, concocting a plan to use occult forces in an attempt to destroy Hitler once and for all.